Nadal retires to send Del Potro into final

NEW YORK: A weary and wounded world number one Rafael Nadal retired from his US Open semifinal while trailing Juan Martin del Potro 7-6(3) 6-2 on Friday, sending the Argentine back to the Flushing Meadows final for the first time since his 2009 triumph.
Nadal, who had never before retired from a US Open match, showed signs of distress almost from the start as he limped noticeably after a gruelling 69-minute opening set.
Grimacing with every sudden move, the 17-time Grand Slam winner called for the trainer during the changeover on serve at 2-1 in the second.
The defending champion had his knee massaged and re-taped and bravely continued through the second set before telling the umpire he was unable to continue.
“I think it was two-all in the first, 15-love, something like this in the first set, that I felt (something),” said Nadal. “I said to my box immediately that I felt something on the knee.
“After that, I was just trying to see if in some moment the thing can improve during the match.
“But no, was not the day.
“I waited as much as I can. You could imagine very difficult for me to say goodbye before the match finish but at some point you have to take a decision.”
Nadal’s stamina and famous fitness have been put to the test on the sweltering Flushing Meadows hardcourts as he has logged nearly 16 hours through five matches.
The Spaniard was made to work for his place in the last four, needing a fifth set tiebreak to see off Dominic Thiem in the quarters. It was the second time this year that the world number one has retired from a slam as he also quit during his quarterfinal against Marin Cilic at the Australian Open in January. — Reuters